What does a tongue piecing mean?
Many people pierce their tongues simply because they think it looks cool. For these people, it's no different than a pierced nose of pierced eyebrow. However, there are people out there who pierce their tongues for sexual reasons. Rumor has it that it feels good during oral sex. You never really know for sure what reason someone has a pierced tongue, and therefore you cannot really say for sure what it means. To do that, you would have to know the individual's motivation for getting the piercing. It means there is a hole through the tongue, probably with jewelry fitted into it. That is the only sure answer to this question since different people do it for different reasons, often with no thought to the significance.
A pimple on your tongue doesn't necessarily MEAN anything in particular; you can get a pimple anywhere, including your face, tongue, lips, etc. Let the pimple heal on its own, do not pop it as bacteria can infect it and yiu can develp acne all over your tongue. A pimple on your tongue COULD mean that a certain food caused it, or you may have had a mild allergic reaction.